The present invention relates to substituted 1,2-naphthoquinone-2-diazide-4-sulfonic acids, and to processes for their preparation and use.
Esters, amides and hydrazides of 1,2-naphthoquinone-2-diazide-sulfonic acids have been used for many years as light-sensitive compounds for radiation-sensitive mixtures such as, for instance, photoresists for the production of semiconductor components in microelectronics or as coating solutions for the production of photomechanically processable printing forms or color proofing films. Suitable compounds and processing methods are described in J. Kosar, Light-Sensitive Systems, John Wiley & Sons, New York, chapter 7.4, 1965, U.S. Pat. No. 4,104,070, U.S. Pat. No. 4,576,901 and EP 0,212,482.
The preparation of the 1,2-naphthoquinone-2-diazide-sulfonic acids on which these known derivatives are based starts from a 1-naphthol-4- or -5-sulfonic acid which is nitrosated with an alkali metal nitrite in a dilute mineral acid. The resulting 2-nitroso-1-naphtholsulfonic acids are isolated, and the unconverted starting materials as well as the by-products formed in the nitrosation are removed by washing out or redissolution. The nitroso compound is then reduced in aqueous solution to the corresponding amino compound. The latter is isolated and again freed of unconverted starting materials and resulting by-products by digestion in water or by redissolution. The amino compound is then suspended in water and diazotized at a pH of 4-6 with an alkali metal nitrite in the presence of Cu(II) salts. In most cases, the 1,2-naphthoquinone-2-diazide-sulfonic acids obtained in this way must still be freed of dark-colored by--products formed in the diazotization by redissolution or recrystallization.
The disadvantage of this known preparation process is that the feed materials unconverted in the individual reaction stages and the by-products formed must be separated by additional purification steps from the desired main product. This entails low yields, a not always satisfactory product quality and high production costs.
EP 283,898 discloses a process for the preparation of benzoquinone- and naphthoquinonediazide-sulfonic acids, which may be substituted by halogen or by nitro or alkyl groups, and of salts thereof. In this case, the starting material is an arylsulfonic acid having at least one hydroxyl group. This acid is nitrosated in the known manner, the resulting nitroso compound is reduced in the alkaline pH range, and the amino compound is then converted into a sulfamate derivative which is subsequently mixed with a diazotizing agent. Acidification of the mixture produces the benzoquinone- or naphthoquinone-diazide-sulfonic acids. The reaction products formed after each reaction step are not isolated, but remain in solution for further reaction ("one-pot reaction"). By-products and impurities which arise in the individual process steps can be separated off in a satisfactory manner by filtering the reaction solution.
The disadvantage of this single-stage process is that the various process steps can be carried out only within a relatively narrow pH range and the reaction times, and reaction temperatures must be adhered to very exactly. The end products obtained by this process are generally not free of isomeric compounds. A universal industrial use of the compounds prepared by this process is therefore restricted.
In German Pat. application No. P 3,837,499.4, which is not a prior publication, a process for the preparation of esters of ring-substituted 1,2-naphthoquinone-2-diazide-4-sulfonic acids is described, wherein 1,2-naphthoquinone-2-diazide-4-sulfonic acids, which are substituted in the 5-, 6-, 7- or 8-position by halogen, alkoxy or alkoxycarbonyl, are obtained as intermediates.
In this case, the starting material is an appropriately substituted 2-naphthol which is nitrosated in the 1-position. The product is sulfonated in the 4-position with an alkali metal hydrogen sulfite and the nitroso group is then reduced to the amino group by acidification with a mineral acid at a pH of about 7 or less. The 2-amino-1-naphthol-4-sulfonic acid is oxidized to the corresponding 1,2-naphthoquinone-4-sulfonic acid and the latter is converted with p-toluenesulfonic acid hydrazide in an organic solvent at temperatures of 20-10? C. to the corresponding ring-substituted,1,2-naphthoquinone-2-diazide-4-sulfonic acid.
Chlorination with chlorosulfonic acid or a chlorosulfonic acid/thionyl chloride mixture gives in a known manner the sulfonic acid chloride which is then condensed with a phenolic component to give the corresponding ring-substituted 1,2-naphthoquinone-2-diazide-4-sulfonic acid esters. The individual process steps for preparing the intermediates and end products are known from the literature. The process is dependent on the relatively poor accessibility of the substituted 2-naphthols which are used as the starting materials. Thus, for example, 7-alkoxy-2-naphthol is obtained according to a known process by monoalkylation of 2,7-dihydroxynaphthalene in a yield of only about 50-55% of theory. The yields of the subsequent reaction stages--nitrosation, sulfonation and reduction, oxidation, introduction of the diazo group--are satisfactory. In spite of the omission of additional purification of the intermediates, the overall yield of 7-alkoxy-1,2-naphthoquinone-2-diazide-4-sulfonic acid, relative to the 2,7-dihydroxynaphthalene employed, is not yet satisfactory, so that the production costs for the sulfonic acid esters which can be prepared are relatively high.
A further process for the preparation of ring-substituted 1,2-naphthoquinone-2-diazide-4-sulfonic acids, which can be used for synthesizing the corresponding esters and amides, is indicated in German Pat. application No. P 3,837,500.1, which is not a prior publication. For the preparation of 7-methoxy-1,2-naphthoquinone-2-diazide-4-sulfonic acid, the starting material is, for example, commercially-available 1-acetylamino-7-naphthol. This can be converted to the desired compound in a 7-stage reaction sequence methylation of the phenolic hydroxyl group, elimination of the acetyl group and preparation of 1-amino-7-methoxynaphthalene hydrogen sulfate, sulfonation in the 4-position by dry heating ("baking reaction"), replacement of the amino group by a hydroxyl group ("Bucherer reaction"), nitrosation in the 2-position, reduction of the nitroso group to the amino group and diazotization. Because of the multi-stage process, process steps which are difficult to carry out on an industrial scale, and the not always satisfactory yield of individual intermediates, this preparation process also raises industrial problems. It is, however, of the greatest importance for the production of photoresists to have available an economical synthesis process for the radiation-sensitive components.
DD 263,982 has disclosed the preparation of 2-diazo-1-oxo-1,2-dihydronaphthalene derivatives, starting from 1,7-dihydroxynaphthalene derivatives. The 1,7-dihydroxynaphthalene-4-sulfonic acid serving as the starting material for this purpose is, however, not easily accessible, so that it is very expensive to carry out the overall process. Moreover, the diazotization of the amino intermediate is possible in acceptable quality only under defined pH and temperature conditions and in the presence of heavy metal salts, and only in a low yield.
The esters and amides of 7-methoxy-1,2-naphthoquinone-2-diazide-4-sulfonic acid are, because of the shift of their absorption to longer wavelengths and because of their high reversal potential, outstandingly suitable for use in photoresist layers which can be structured in the g line (436 nm) and i line (365 nm) regions and can be processed either positively or negatively.